There are a bunch of resources on the FOG - try a search for "boom arm".
Here are some that you'll particularly like, although most are "pre-picturegate" and so the detailed photos are likely lost (there was unfortunately a catastrophic loss of photos on the forum a year or so ago).
The Rick Christopherson build out...
http://festoolownersgroup.com/fun-games-diversions/something-wicked-this-way-comes/
As a lot of the photos will have gone, hopefully this link might help too...
http://www.talkfestool.com/vb/woodworkers-cafe/4402-something-wicked-way-comes.html
Also this; don't know whether [member=20326]SittingElf[/member] has his installed yet...
http://festoolownersgroup.com/festo...r-rick-christopherson-regarding-the-asa-5000/
And this is a personal favourite although [member=1466]Michael_Swe[/member] hasn't been around for quite a while...
http://festoolownersgroup.com/festool-jigs-tool-enhancements/boom-arm-deluxe/
I only saved one photo unfortunately [crying]
View attachment 1
This shows one attached to the wall which you specifically asked about...
http://festoolownersgroup.com/festool-tools-accessories/boom-arm/
This is a home-made version of the ASA boom; use Google Chrome to auto-translate...
http://www.woodworking.de/blog/2013/02/werkstatt-von-michael-b/
Hope these help with your thoughts.